How do I make bone drivers work?
There are alternatives, such as this, but you have to accept that rigging is a technical skill, so my advice is to let those brain cells burn, and ask here what exactly you don't understand.

Note that in 2.78 drivers were improved, but this means that older tutorials became a bit confusing.

Another alternative is to create only thin, skinny characters because they usually deform acceptably with correct weight painting, and the drivers are not needed.